So far, for example, Patent Document 1 discloses a control apparatus for an internal combustion engine that executes learning control for small fuel injection amount in order to improve the accuracy of small injection such as pilot injection that is included in the multi injection. More specifically, this learning control of the small fuel injection amount executes a fuel injection (small injection) with small amount when a fuel cut operation is performed at the time of deceleration, and is executed based on the relation between the fuel injection amount at this time and a generated torque of the internal combustion engine.
Meanwhile, the following configuration is known as that of a fuel injection valve used for an internal combustion engine. More specifically, a fuel injection valve is known which includes a needle valve that has a seat contact part at its distal end, and a nozzle body that has a seat part with which the seat contact part comes into contact, and further includes a fuel receiving part (so-called suck or the like corresponding thereto) formed at a downstream side of the seat part, and at least one nozzle hole formed at a downstream side of the seat part.
According to the fuel injection valve having the configuration described above, injection characteristics such as injection amount characteristics change whether the valve is in a state in which the fuel amount charged in the fuel receiving part is large (liquid-tight state) or a state in which the fuel amount charged in the fuel receiving part is small (gas-tight state). Therefore, if the learning control of the small fuel injection amount described in Patent Document 1 is executed in the internal combustion engine including a fuel injection valve having the aforementioned configuration, the fuel injection amount actually injected from the needle holes fluctuates depending on whether the internal state of the fuel receiving part is in the liquid-tight state or the gas-tight state. As a result of this, a variation (erroneous learning) may occur in the learned value of the fuel injection amount. If a proper correction for the fuel injection amount by means of the small injection such as the pilot injection is not executed due to the influence of the variation of the learned value, there is a concern that misfire may occur at the time of low load operation or smoke emissions may increase at the time of high load operation.
Including the above described document, the applicant is aware of the following documents as related art of the present invention.